Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

doi:10.1103/PhysRevLett.118.251801

	Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay
	Daya Bay Collaboration
刊名	PHYSICAL REVIEW LETTERS
	2017
卷号	118 期号:25 页码:251801
ISSN号	0031-9007
DOI	10.1103/PhysRevLett.118.251801
文献子类	Article
英文摘要	The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW(th) reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective Pu-239 fission fractions F-239 from 0.25 to 0.35, Daya Bay measures an average IBD yield (sigma) over bar (f) of (5.90 +/- 0.13) x 10(-43) cm(2)/fission and a fuel-dependent variation in the IBD yield, d sigma(f)/dF(239), of (-1.86 +/- 0.18) x 10(-43) cm(2)/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the Pu-239 fission fraction at 10 standard deviations. The variation in IBD yield is found to be energy dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1 sigma. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes U-235, Pu-239, U-238, and Pu-241. Based on measured IBD yield variations, yields of (6.17 +/- 0.17) and (4.27 +/- 0.26) x 10(-43) cm(2)/fission have been determined for the two dominant fission parent isotopes U-235 and Pu-239. A 7.8% discrepancy between the observed and predicted U-235 yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.
电子版国际标准刊号	1079-7114
WOS关键词	NEUTRON FISSION-PRODUCTS
WOS研究方向	Physics
语种	英语
WOS记录号	WOS:000403560000001
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/284522]
专题	高能物理研究所_实验物理中心
作者单位	中国科学院高能物理研究所
推荐引用方式 GB/T 7714	Daya Bay Collaboration. Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay[J]. PHYSICAL REVIEW LETTERS,2017,118(25):251801.
APA	Daya Bay Collaboration.(2017).Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay.PHYSICAL REVIEW LETTERS,118(25),251801.
MLA	Daya Bay Collaboration."Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay".PHYSICAL REVIEW LETTERS 118.25(2017):251801.